JPS63228789A - Photo-semiconductor and manufacture thereof - Google Patents

Abstract

PURPOSE:To simplify the coupling of a semiconductor laser with an optical fiber and to improve the reproducibility of the coupling efficiency or the like by providing a resin shaped in a convex lens for focussing the optical output and controlling the emission direction in the optical output section of the semiconductor laser. CONSTITUTION:The emitted light from the resonator surface is upwardly reflected at a reflecting surface which is inclined by about 45 deg. with respect to the principal surface of a semiconductor substrate 1 positioned in front, and is focussed by a polyimide resin 10 of the shape of a convex lens formed between the resonator surface and the reflecting surface. And the emission direction of the focussed optical output is made variable by changing the position of the polyimide resin 10, whereby the oblique angle of the reflecting surface becomes constant. The polyimide resin 10 is shaped into a convex lens by selectively forming a photo resist 53 on the surface of a polyimide resin 52 formed on a semiconductor substrate 51, and isotropically etching the polyimide resin 52 and the photo resist 53 in an oxygen plasma atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to optical semiconductor devices such as semiconductor lasers (Ll) and light emitting diodes (LEDs) used as light sources in optical fiber communications, etc., and to conventional techniques for manufacturing the same. Since the invention of the 5GmAg/GaAs double helix structure semiconductor laser, the performance of semiconductor lasers has progressed rapidly, and today, high-performance and high-performance lasers with oscillation thresholds of several tens of mA and lifetimes of several hundred thousand hours have been made. Reliable products have even reached the point where they are commercially available. In terms of applications for semiconductor lasers, electronic devices such as CDs (compact discs) and optical discs that record and reproduce large amounts of information on small media at high density are beginning to become commercially available. Semiconductor lasers are also used as light sources for optical fiber communications, and they are used to connect cities with optical fibers to transmit information, and to transmit information within factories and offices as in LAN (Local Area Network). The range of applications for semiconductor lasers is gradually expanding, including being used for transmission. As described above, various structures have been proposed as useful semiconductor laser structures. For example, S, M,
Physics of Semiconductor Devices by Sze
f Sem1-conductor Devices
) 2nd edition 1981 John Wiley & 5on
As shown on page 726 of S Publishing, there are various types of structures.

Each of these semiconductor lasers has a stripe-shaped current injection portion, and a pair of resonator surfaces formed by cleavage are provided at both ends of the stripe. However, in this cleavage process, it is difficult to make the length of the resonator constant with good reproducibility or to obtain a good resonator surface (cleavage surface) with a high yield. In addition, it is not possible to evaluate the optical output, quantum efficiency, oscillation threshold, etc. of these semiconductor lasers unless they are cleaved, so the inspection to distinguish between good and bad semiconductor lasers takes time and is difficult for mass production. Ta.

Furthermore, it is difficult to form a plurality of lasers in an array on the same substrate.

Therefore, as a way to solve these problems, for example, Applied Fixtures
Physics Letters, Volume 46, No. 2, No. 1
As shown on pages 16 to 117 (1985), a semiconductor laser cavity is formed by chemical etching, and a mass transport method is used to form a semiconductor laser cavity on the substrate surface in order to emit the emitted light perpendicular to the substrate surface. On the other hand, a method of providing a concave reflecting plate tilted at 46° has been proposed by Z, L, L, et al. (see FIG. 1 of the above-mentioned document). According to this method, cleavage is not required to form a semiconductor laser, and the optical output is emitted perpendicular to the substrate surface, so characteristics such as optical output, quantum efficiency, and oscillation threshold can be maintained as is. Since it can be evaluated, the time required for inspection is shortened. Further, there is an advantage that a cleavage step with poor yield and reproducibility is not required. Furthermore, since the reflecting plate is a concave mirror, there is an advantage that the emitted light is focused.

Problems to be Solved by the Invention Although the semiconductor laser having the 46° reflection surface has various advantages as described above, it also has the following problems in the manufacturing process of the device.

(1) The reproducibility when manufacturing a 45° reflective surface formed by mass transport is poor. That is, according to the inventors' experiments, mass transport is greatly influenced by the surface condition of the substrate at the time of mass transport. Therefore, it was difficult to create a reflective surface having an angle of 46° with good reproducibility. Therefore, it is difficult to improve the reproducibility of the output angle of the output light with respect to the main surface of the semiconductor substrate, and the coupling efficiency when coupling the output light to the optical fiber varies.

(2) Dust tends to accumulate in the groove between the resonator surface and the 46° reflection surface, and the emitted light is scattered by the dust.

Means for Solving the Problems The present invention has been made in view of the problems in conventional semiconductor lasers as described above. It has a structure including resin.

Effects The above-described configuration has the following effects. (1) Outgoing light is focused with a convex lens-shaped resin. (2)
Since the output angle can be varied depending on the relative positional relationship between the position of the convex lens and the position from which the light output is emitted, the output angle can be freely set according to the purpose.

(3) Since the groove between the resonator surface and the reflection plate is filled with resin, no dust will accumulate.

EXAMPLE An example in which the present invention is applied to an InGaAg P semiconductor laser will be described. FIG. 1 shows a cross-sectional view of a semiconductor laser according to an embodiment of the present invention. In FIG. 1, 1 is a semi-insulating InP substrate, 2 is an n+ type InP first ground layer, and 3 is an InP substrate with a bandgap wavelength λg=L3pm.
GaAs P active layer, 4 is a p-type InGaAs P optical waveguide layer, 6 is a p + type InP second cladding layer, e is a p-type InGa S contact layer, 7 and 8 are layers for increasing the reflectance of the cavity surface. They are a SiO□ film, an amorphous S1 film, and a 10id polyimide resin, respectively. In Figure 1, the dotted line indicates the optical output, and the light emitted from the resonator surface is reflected upward by a reflective surface tilted at approximately 45 degrees with respect to the main surface of the semiconductor substrate in front of the resonator surface. . In the present invention, a convex lens-shaped polyimide resin 10 is used as shown in FIG.
is formed between the resonator surface and the reflective surface, so the emitted light is focused. The light emitted from the end face of the laser resonator has a divergence angle of about 30°, but polyimide resin 1
0 and a divergence angle of about 10°. Further, as shown in FIG. 1, since polyimide resin 10 is embedded in the groove formed between the resonator surface and the reflective surface, no dust will accumulate in the groove.

The present invention is not limited to being able to obtain a focused light output using the polyimide resin 10 as described above, but it is also possible to make the output direction of the light output variable. The situation is schematically shown in FIGS. 2a, b, and c.

In FIGS. 2a, b, and c, 21 is a semiconductor substrate, 22 is an active layer, 23 is a cladding layer, and 24Vi convex lens-shaped polyimide resin. The dotted lines indicate the light output, but in Figure 2 a, b,
It can be seen that the direction of light output can be changed by changing the position of the polyimide resin 24 as shown in c. For example, when an optical fiber is arranged perpendicularly to the main surface of the semiconductor substrate 21 and the optical output is emitted perpendicularly to the main surface of the semiconductor substrate 21, the light reflected from the end face of the optical fiber returns to the end face of the common camera and generates noise. Therefore, it is better to have the light output at an angle rather than vertically.

Furthermore, if the optical output is too inclined with respect to the optical fiber, the coupling efficiency will deteriorate. In the case of the present invention, when the reflective surface is made of (111) human blood, for example, the inclination angle of the reflective surface can be made constant, so by precisely aligning the polyimide resin 24, the direction of light output can be adjusted, for example. 6° to the normal to the main surface of the semiconductor substrate 21
It is possible to obtain tilted optical output with good reproducibility.

FIG. 3 shows a method for processing polyimide resin into a convex lens shape. First, as shown in FIG. 3B, a photoresist 63 is selectively formed on the surface of the polyimide resin 52 formed on the surface of the substrate 51. Then, as shown in FIG.

Next, this sample is placed in an oxygen plasma atmosphere and the polyimide resin 52 and photoresist 53 are etched.

During this etching, the pressure of the atmosphere is reduced to 0.5, for example.
When the temperature is set to Torr, the polyimide resin 62 and the photoresist 53 are etched isotropically, and the polyimide resin 62 is processed into a convex lens shape as shown in FIG.

Effects of the Invention According to the present invention, by providing a resin in the shape of a convex lens in the light output section of a semiconductor laser, it is possible to focus the light output and control the output direction of the light output. Therefore, the coupling between the semiconductor laser and the optical fiber is facilitated, and the reproducibility of the coupling efficiency and the like is improved, so the industrial value is high.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a sectional view showing a semiconductor laser according to an embodiment of the present invention, FIG. The figure is a process sectional view for explaining a method of processing a polyimide resin into a convex lens shape in the same laser manufacturing method. 10.24.52...Polyimide resin, 63.
...Photoresist. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
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Claims (2)

[Claims] (1) An optical semiconductor device comprising a convex lens-shaped resin on a surface that emits optical output substantially perpendicularly to the main surface of a semiconductor substrate. (2) forming a resin on the main surface of the semiconductor substrate; selectively forming a photoresist on the surface of the resin;
A method for manufacturing an optical semiconductor device, comprising the step of etching the resin and the photoresist with oxygen plasma to form a convex lens shape.